This is a proposal to investigate a novel dilation device that does not contain a folded balloon element. Dilation devices are widely used in the medical profession, usually as a component part of a catheter. Such catheters are usually referred to as balloon catheters. Balloon catheters are constructed by folding a deflated balloon around a catheter shaft. Our new device eliminates the folded balloon wrapped about a catheter. The device is suitable for use as the expansive element in angioplasty and other catheters. The device consists of a thin wall segment in a catheter whose outer diameter matches the outer diameter of the catheter. The thin wall segment expands upon the application of pressure to the interior of the catheter. Due to its low profile, it has the potential to reduce the size of currently available balloon catheters thereby extended the applicability of angioplasty to situations currently reserved for by-pass surgery. PROPOSED COMMERCIAL APPLICATION: Coronary angioplasty, neurological angioplasty, periferal angioplasty, stent delivery system, dilation of non arterial lumens such as biliary or kidney related.